Multiple radio frequency (RF) signal reception is becoming and will certainly be a key capability in current and future radio communications. It has already begun to be used in Long-Term Evolution (LTE)-Advanced and is a key feature of 5G New Radio (NR) (the next major cellular standard after LTE) because of the high data rates it enables; specifically, carrier aggregation allows for the use of up to five carriers in LTE-Advanced and up to sixteen carriers in 5G NR to increase data rates. With the overcrowded nature of frequency spectrum due to limited spectrum resources, cognitive radios will need to be able to dynamically receive multiple signals at carrier frequencies that change with time. While the prior art does not address this issue, it may be desirable to consider methods of reducing computational complexity in RF receivers from a holistic perspective for multiple signal reception applications. Typically others try to minimize the complexity at each stage of the signal reception process which does not necessarily result in the lowest complexity when looked at from a larger perspective. For example, using the smallest valid sampling rate to sample multiple signals without considering where the signals are placed after sampling. Another example is taking the signal placement at the input to a polyphase downconverter channelizer as a given and introducing additional computational complexity in the channelizer or at its output to process signals not falling entirely within one of the input channels.
Bandpass sampling of a single analog RF signal is well known. This will be described with reference to FIG. 1.
FIG. 1 illustrates a prior art bandpass-filtering system 100, which includes an antenna 102 and a receiving portion 104. Receiving portion 104 includes a bandpass filter, and LNA component 106 and an ADC component 108.
In operation, antenna 102 receives an analog radio frequency (RF) signal 118, having a carrier frequency. Antenna 102 passes analog RF signal 118 to receiving portion 104 via line 112. Bandpass filters and LNA component 106 bandpass-filters and amplifies analog RF signal 118 so as to output amplified filtered analog RF signal 120 to ADC component 108 via line 114. ADC component 108 samples amplified filtered analog RF signal 120 at a predetermined sample rate that is below its Nyquist rate and that is still able to reconstruct the signal. ADC component 108 outputs an intermediate frequency (IF) digital signal 122 that corresponds to amplified filtered analog RF signal 120 via an output line 116 for further processing (not shown).
Further using a polyphase downconverter channelizer to separate a plurality of received signals is well known. What is needed is a system and method that determines a minimum sampling frequency, Fs, for use in the bandpass sampling of a plurality of received signals.